<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        * {
            padding: 0;
            margin: 0;
        }

        .box {
            width: 500px;
            height: 200px;
            border: 1px solid #ccc;
            margin: 50px auto;
            overflow: hidden;
        }

        ul {
            width: 600px;
            height: 40px;
            margin-left: -1px;
            list-style: none;
        }

        li {
            float: left;
            width: 101px;
            height: 40px;
            text-align: center;
            font: 600 18px/40px "simsun";
            background-color: pink;
            cursor: pointer;
        }

        span {
            display: none;
            width: 500px;
            height: 160px;
            background-color: yellow;
            text-align: center;
            font: 700 100px/160px "simsun";
        }

        .show {
            display: block;
        }

        .current {
            background-color: yellow;
        }
    </style>

    <script>
        window.onload = function () {
            //需求：鼠标放到上面的li上，li本身变色(添加类)，下方对应的span也显示出来(添加类);
            //思路：1.点亮上面的盒子。   2.利用索引值显示下面的对应的盒子。

            //1、获取所有的box
            var boxArr = document.getElementsByClassName("box");

            //让每一个box都调用函数
            for (var i = 0; i < boxArr.length; i++) {
                fn(boxArr[i]);
            }

            function fn(element) {
                var liArr = element.getElementsByTagName("li");   //注意，是element获取事件源，不是document获取事件源
                var spanArr = element.getElementsByTagName("span");
                //2.绑定事件（循环绑定）
                for (var i = 0; i < liArr.length; i++) {
                    //绑定索引值（新增一个自定义属性：index属性）
                    liArr[i].index = i;
                    liArr[i].onmouseover = function () {
                        //3.书写事件驱动程序（排他思想）
                        //1.点亮上面的盒子。   2.利用索引值显示下面的盒子。(排他思想)
                        for (var j = 0; j < liArr.length; j++) {
                            liArr[j].className = "";
                            spanArr[j].className = "";
                        }
                        this.className = "current";
                        spanArr[this.index].className = "show"; //【重要】核心代码
                    }
                }
            }
        }
    </script>
</head>
<body>

<div class="box">
    <ul>
        <li class="current">鞋子</li>
        <li>袜子</li>
        <li>帽子</li>
        <li>裤子</li>
        <li>裙子</li>
    </ul>
    <span class="show">鞋子</span>
    <span>袜子</span>
    <span>帽子</span>
    <span>裤子</span>
    <span>裙子</span>
</div>

<div class="box">
    <ul>
        <li class="current">鞋子</li>
        <li>袜子</li>
        <li>帽子</li>
        <li>裤子</li>
        <li>裙子</li>
    </ul>
    <span class="show">鞋子</span>
    <span>袜子</span>
    <span>帽子</span>
    <span>裤子</span>
    <span>裙子</span>
</div>

<div class="box">
    <ul>
        <li class="current">鞋子</li>
        <li>袜子</li>
        <li>帽子</li>
        <li>裤子</li>
        <li>裙子</li>
    </ul>
    <span class="show">鞋子</span>
    <span>袜子</span>
    <span>帽子</span>
    <span>裤子</span>
    <span>裙子</span>
</div>

</body>
</html>
